1. Field Of the Invention
The present invention is directed to an x-ray examination apparatus of the type having a stand composed of at least one base, a holder for a curved carrier rotatable around a horizontal axis and connected to the base, an x-ray tube and an x-ray receptor (detector) being secured to the carrier, a fastening means for the stand and an arm that connects the stand to the fastening means, with the one end of the arm being rotatable around an axis at the fastening means, as well as having an examination table that is displaceable at least along its center line.
2. Description of the Prior Art
It is of significance in conjunction with radiological heart examinations that the x-ray tube and the receptor be able to sweep the upper body of the patient to the groin. It is also desirable in other examinations to sweep the entire length of the patient. In such examinations, the apparatus stand can be attached to the long side of the examination table and can be displaced parallel with the examination table, permitting the aforementioned patient region to be reached without difficulty with the x-ray tube and the receptor. Such an examination apparatus is known from the Siemens brochure "ANGIOSTAR" wherein the stand is displaceable in floor rails. Given such an examination apparatus, the physician has extremely good access to the patient at the head end and at the long side of the table but, of course, not from the side at which the stand is attached.
A stand attached at the head end is known in another type of x-ray examination apparatus wherein the inside diameter of the curved carrier defines how far the x-ray tube and the receptor can sweep the body of the patient when the head end of the examination table is placed in the carrier arc between the x-ray tube and the receptor tightly against the holder of the carrier arc. Such an examination apparatus is described in the Siemens brochure "COROSKOP HS". The problem involving motion limitations of the x-ray tube and of the receptor due to the shape of the carrier arc is partially resolved given this examination apparatus because the stand, which is placed on the floor, is rotatable around a vertical axis and can be combined with an examination table suspended at the ceiling, which can be displaced in a longitudinal direction as well as laterally relative to the longitudinal direction, or can be combined with an examination table attached to the floor that is rotatable around a vertical axis. The position of the examination table must be set with every rotation of the stand around the vertical axis.
The brochure "Advantx L/C" of GE Medical Systems describes an x-ray examination apparatus of the type initially described. The axis of the fastening means around which the arm is rotatable is applied to the floor and, as viewed from above, is attached on the imaginary center line of the examination table under the head end of the table. Due to the arm that extends under the table, the stand together with the carrier for the x-ray tube and the receptor can be turned around the axis of the fastening means from a position wherein the carrier is attached to the head end of the table into a further position wherein the carrier is arranged at an angle of 90.degree. relative to the longitudinal direction of the table. The stand is constructed such that the center line between the x-ray tube and the receptor lies axially aligned with the axis in the fastening means given a vertical adjustment. The imaginary center line between the x-ray tube and the receptor is therefore always fixed in the same isocenter given a rotation of the stand around the axis of the fastening means. The available amount of longitudinal displacement of the table determines how large the part of the patient that can be examined is. Since the arm placed at the floor is comparatively broad and high in the region of the axis of the fastening means, the physician can bump against the arm with his or her feet during the examination; this can be disturbing. Due to the position and size of the arm, the carrier for the x-ray tube and the receptor cannot be lowered down to the floor given a vertical attitude. In such a vertical attitude, a lowering of the x-ray tube and of the receptor by 4-5 cm, this being estimated to be the thickness of the arm, can be critical in some instances in order to obtain a good exposure.
The Philips brochure "Integris BN 3000 und Integris BV 3000" shows and describes a further stand that can change between a head position and a side position. This stand is constructed such that the holder for the carrier to which the x-ray tube and the receptor are secured is directly attached to the fastening means at the floor and can be turned around the vertical axis thereof. The axis of the fastening means is arranged under the head end of the examination table and, as viewed from above, is placed at the imaginary center line of the examination table. The center line of the x-ray tube and of the receptor given a vertical attitude is also arranged in alignment here with the axis of the fastening means. Due to this structure, the center line for the x-ray tube and the receptor does not have an imaginary isocenter given a swiveling of the holder and of the carrier. Again, the size of the part of the patient that can be examined is also dependent on the size of the longitudinal displacement of the table. Due to the structure of the stand, this carrier also cannot be lowered down to the floor.